The studies proposed are concerned primarily with characterizing the metabolites of testosterone formed in different areas of the brain, in particular, in the hypothalamus and in elucidating their role in certain CNS functions. The functions under investigation will be certain aspects of gonadotrophin regulation, aggressive and sexual behavior. The role of these metabolites in the differentiation and activation of these functions will be investigated. Most of the basic work will be carried out using rats. In human subjects the investigation will focus on establishing correlations between functional or behavioral disorders and circulating steroid levels.